As far as the current or future communication technology is concerned, the optical fiber communication is an indispensable tool. Like the cable communication system in which the signal cable and the signal connector are joined together, the optical fiber communication involves the use of the optical fiber connector. In the process of forming the optical fiber connector, an optical fiber is put through the hole of a ring such that the optical fiber is attached to the ring by an adhesive. The ring is made of a plastic, glass, or ceramic material. The end of the optical fiber attached to the ring is pressured on an elastic grinding surface and is then treated with a preliminary grinding process, a precision grinding process, and a polishing process, thereby resulting in the formation of a convex spherical face. The convex spherical face must be devoid of any defect. The optic axis of the convex spherical face may be parallel to the center line of the optical fiber or may form a small angle along with the center line of the optical fiber. The current grinding technology of the optical fiber end is basically evolved from the grinding technology of the optical lens. The manual grinding technology was followed by the machine grinding technology as illustrated in FIG. 1. Such a conventional method for grinding an optical lens involves the use of a grinding tray 10, which is provided with a grinding surface of cast iron in the course of the preliminary grinding and the precision grinding. The grinding tray 10 is provided with a grinding surface of asphalt or other polishing materials in the course of the polishing. In the grinding and the polishing processes, the grinding powders and the polishing powders of various grain densities are used along with water. The conventional method also involves the use of a workpiece holder to which a grinding workpiece assembly 2 is attached. The assembly 2 may be moved leftward and rightward in a reciprocating manner. The assembly 2 may be stationary. In case of an appropriate movement, the grinding surface in its entirety may be able to maintain a constant curvature due to the uniform wear. If the grinding surface is turned counterclockwise at ω angular speed, the workpiece assembly is also caused to turn counterclockwise by virtue of frictional force. In the absence of a special arrangement, these two angular speeds will not be equal to each other. At the conclusion of the preliminary grinding and the precision grinding, curvature of the lens is almost in line with the requirement. The workpiece is finally polished in such a manner that the polishing is done from the fringe of the workpiece toward the central part of the workpiece, and that curvature of the workpiece conforms to specifications. The grinding process and the polishing process may last as long as thirty minutes. As far as the conventional method for grinding the optical lens is concerned, the wear is greater at the fringes of the workpiece than at the inner part of the workpiece.
The grinding technology of the optical fiber end was developed two decades ago from the conventional method for grinding the optical lens. The grinding process of the optical fiber end is carried out in such a manner that the optical fiber is attached to the ring, and the holder of the optical fiber end must be stationary. In light of the relative motion of the workpiece and the grinding tray of the conventional method for grinding the optical lens, the grinding surface must be caused to engage in a movement or rotation of other form in relation to the optical fiber end holder in addition to its self-revolution, as shown in the U.S. Pat. Nos. 4,831,784; 4,905,415; 4,979,334; and 5,458,531. The most commonly-used grinding tray movement is illustrated in FIG. 2 in which the reference numerals 3, 4, and 5 denote respectively an optical fiber end holder, self-revolution of a grinding surface, eccentric rotation of the grinding surface. The prior art methods for grinding the optical fiber end are technically similar to the conventional method for grinding the optical lens such that the wear is greater at the fringe of the optical fiber end than the inner part of the optical fiber end.
The precision grinding and the polishing of the optical fiber end are done on an elastic grinding surface, as illustrated in FIG. 3 in which the reference numerals 7, 8, and 9 denote respectively a workpiece, a pressure, and an elastic grinding surface. The elastic grinding surface 9 is exerted on by the pressure 8 such that the elastic grinding surface 9 is caused to have a depression by means of which the workpiece 7 is so shaped as to have a convex surface. In view of the fact that the workpiece to be shaped by the elastic grinding surface is relatively small in size, the time that is required for the preliminary grinding, the precision grinding and the polishing lasts less than thirty seconds, which are considerably short as compared with the conventional method for grinding the optical lens. It is therefore necessary that all optical fiber ends held by the holder must be subjected to the same grinding strength in a relatively short period of time. In other words, the optical fiber ends are located at positions which are equal in grinding strength to one another. For example, twelve optical fiber ends are arranged along the circumference of a round holder such that all optical fiber ends are exerted on by the same pressure, thereby resulting in the shaping of all optical fiber ends in a uniform manner. Such a control method is respectively disclosed in the U.S. Pat. Nos. 6,039,630; and 6,077,154. These prior art methods are limited in design in that the optical fiber end holder can accommodate only a few optical fiber ends, and that they are not suitable for use in mass production.